KR101482695B1 - Organic thin film transistors, organic light-emissive devices and organic light-emissive displays - Google Patents

Abstract

A dopant moiety for chemically doping the organic semiconductor material by the acceptance or donation of charges and a source electrode coupled to the dopant moiety for depositing source and drain electrodes and on the source 2 and drain 4 electrode surfaces, Forming a thin film self-assembled layer 14 of a material including a separate attachment moiety selectively coupled to a source electrode and a drain electrode; depositing a solution containing a solvent and an organic semiconductor material 8 in a channel region between the source and drain electrodes Wherein the organic thin film transistor includes a first electrode and a second electrode.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to organic thin film transistors, organic light emitting devices, organic light emitting displays, organic light emitting displays, organic light emitting devices,

An object of the present invention is to provide an organic thin film transistor and a manufacturing method thereof. Still another object of the present invention relates to an organic light emitting device and a method of manufacturing the same. It is another object of the present invention to provide an organic light emitting display including an organic thin film transistor and an organic light emitting device and a method of manufacturing the same.

Transistors can be divided into two main types: bidirectional junction transistors and field effect transistors. These two types share a common structure including three electrodes and a semiconductor material disposed therebetween in the channel region. Three electrodes of a bidirectional junction transistor are known as emitters, collectors and bases, and three electrodes of a field effect transistor are known as sources, drains and gates. A bidirectional junction transistor will be described as a current drive because the current between the emitter and the collector is controlled by the current flow between the base and the emitter. Conversely, a field effect transistor will be described as a voltage-driven transistor because the current flow between the source and the drain is regulated by the voltage between the gate and the source.

Transistors can also be classified as p-type and n-type, respectively, depending on whether the semiconductor material contained therein conducts either positive charge carriers (positive holes) or negative charge carriers (electrons). The semiconductor material is selected according to its chargeability, conductivity and donor ability. The acceptability, conductivity and donor ability of the hole or electron of the semiconductor material can be increased by doping the material. Further, the material for the source and drain electrodes can be selected according to their ability to accept and introduce holes or electrons. For example, a p-type transistor device can be manufactured by selecting a semiconductor material that is effective for accepting, conducting, and donating holes, and by selecting materials for source and drain electrodes that are effective for introducing and receiving holes from the semiconductor material. In the electrode having the HOMO level of the semiconductor material, a good energy level corresponding to the Fermi-level can increase the hole introduction and acceptance. On the other hand, the n-type transistor device selects a semiconductor material that is effective for receiving, conducting, and donating electrons, introduces electrons into the semiconductor material, and selects materials for the source and drain electrodes that are effective for receiving electrons from the semiconductor material . A good energy level in accordance with the Fermi level in the electrode having the LUMO level of the semiconductor material can increase the acceptance and acceptance of electrons.

A transistor can form a thin film transistor by depositing the components in a thin film. When an organic material is used as a semiconductor material among these devices, this is known as an organic thin film transistor.

Several arrangements for organic thin film transistors are known. One such device is an insulated gate field effect transistor, comprising a semiconductor material disposed between and within the channel region with source and drain electrodes, a gate electrode disposed adjacent to the semiconductor material, and a gate electrode disposed within the channel region, And an insulating material layer disposed between the semiconductor materials.

An example of the organic thin film transistor is shown in Fig. The structure shown includes source and drain electrodes 2, 4 that can be deposited on the surface of a substrate (not shown) and are spaced apart by a channel region 6 located therebetween. The organic semiconductor (OSC) 8 may be deposited in the channel region 6 and extend over at least a portion of the source and drain electrodes 2, 4 . An insulating layer 10 of dielectric material of the organic semiconductor 8 And may extend over at least a portion of the source and drain electrodes 2, 4 . Finally, the gate electrode 12 of the insulating layer 10 ≪ / RTI > The gate electrode 12 is electrically connected to the channel region 6 And extend over at least a portion of the source and drain electrodes 2, 4 .

The above-described structure is known as a top-gate organic thin film transistor because the gate is located on the upper side of the device. It is also known to provide a gate on the bottom side of the device to form a so-called battom-gate organic thin film transistor.

An example of the bottom-gate organic thin film transistor is shown in Fig. In order to more clearly show the relationship between the structures shown in Figs. 1 and 2, the same reference numerals are used for corresponding parts. The bottom-gate structure shown in FIG. 2 includes an insulating layer 10 of dielectric material deposited thereon with a gate electrode 12 deposited on the substrate 1 . The source and drain electrodes 2, 4 are deposited on an insulating layer 10 of dielectric material. The source and drain electrodes 2, 4 are spaced apart by a channel region 6 located therebetween on the gate electrode. An organic semiconductor (OSC) 8 may be deposited in the channel region 6 and extend over at least a portion of the source and drain 2, 4 .

One challenge with all organic thin film transistors is to ensure good ohmic contact between the source and drain electrodes and the organic semiconductor (OSC). This is required for minimizing the contact resistance when the thin film transistor is driven. For a p-channel device, a typical approach for minimizing extraction and introduction barriers is to select a material for the source and drain electrodes, where the work function is well matched to the HOMO level of the OSC. For example, many conventional OSC materials have good conformance of the HOMO level to the work function of gold, making gold a relatively good material for the source and drain electrode materials. Similarly, for n-channel devices, a typical approach for minimizing extraction and introduction barriers is to select materials for the source and drain electrodes that work well with the LOMO level of the OSC.

One problem with the above arrangement is that there are relatively few materials that can have a good energy level work function consistent with the HOMO / LUMO of the OSC. The majority of these materials are expensive such as gold and / or deposition may be difficult to form the source and drain electrodes. Moreover, even if a suitable material is available, the material may not perfectly match the desired OSC, and a change in the OSC may require a change in the material for the source and drain.

One known solution is to provide a self-assembled dipole layer on the source and drain electrodes to improve compliance with the energy level. Though not wishing to be bound by theory, it is believed that the thin film self-assembled dipole layer shifts the energy level of the source / drain electrode material and / or the energy level of the OSC close to the source / drain electrode to form the energy level between the OSC and the source / So that the electric field can be improved.

Using a self-assembled dipole layer, it is possible to improve the degree of conformity between the energy levels of the source / drain material and the OSC, but the energy levels can only be varied by a few tenths of a volt of electrons using this technique have. As described above, the kinds of materials used for the source and drain electrodes are still relatively limited. The materials can be selected for their process compatibility and thus have the advantage of using a wide range of source and drain materials. Another problem is that when the thin film self-assembled dipole layer is disposed within the channel region as well as the source / drain electrode surface, the performance characteristics of the OSC in the channel region may be adversely affected.

Various other approaches have been used in the prior art to improve the performance of organic thin film transistors.

In US 2005/133782, substituted benzonitriles such as benzonitrile or tetracyanoquinodimethane (TCNQ) are used to facilitate charge transfer between organic semiconductor and source / drain electrode surfaces, and source / drain A method of doping a palladium metal is disclosed. Unlike the dipole layer, which only changes the energy levels of the OSC and / or source and drain using the field effect described above, the benzonitriles chemically dope the OSC by accepting electrons (p-doping). As such, the conductivity of the OSC near the electrodes is increased and the charge transport is much more facilitated than using the dipole layers described above.

In US 2005/133782, the nitriles are directly attached to the source / drain metal without being functionalized with specially designed groups. In US 2005/133782, the dopant nitrile groups themselves are capable of bonding to the source / drain palladium metal and the unbonded dopants are removed by washing leaving the dopant nitrile groups attached to the source / drain, And it can be made not to remain in the channel.

It is an object of certain embodiments of the present invention to provide an improved method of processing the source / drain electrodes to provide good ohmic contact between the source / drain electrodes and the organic semiconductor material in the improved organic thin film transistor and organic thin film transistor.

Referring to FIG. 6, the structure of the organic light emitting device is shown. The organic light emitting device includes a transparent glass or plastic substrate 100 , for example, an anode 102 made of indium tin oxide and a cathode 104 . An organic light emitting layer 103 is provided between the anode 102 and the cathode 104 .

In operation, holes are introduced into the device through the anode, and electrons are introduced into the device through the cathode. These holes and electrons are bonded to the organic light emitting layer to form an exciton, where the excitons are radiatively decayed to emit light (this process is essentially reversed in the light detecting device ).

Other layers, such as a charge transport layer, a charge injection layer, or a charge blocking layer, may be disposed between the anode 102 and the cathode 104 .

In particular, it is desirable to provide a conductive major doping layer 105 formed of a doped organic material located between the anode 2 and the organic light emitting layer 3 to assist in the introduction of holes from the anode into the semiconductor polymer layer (s). Examples of doped organic hole injection materials include poly (ethylene dioxythiophene) (PEDT), especially PEDT doped with polystyrene sulfonate (PSS) as described in EP 0901176 and EP 0947123, 5723873, and polyaniline as described in US-A-5798170.

Further, it is preferable to provide the semiconductor hole transporting layer 106 located between the conductive hole transporting layer 105 and the organic light emitting layer 103 . Preferably, the HOMO level of the hole transport layer 106 is less than or equal to 5.5 eV, and more preferably about 4.8 to 5.5 eV.

When the electron transporting layer is present between the organic light-emitting layer 3 and the cathode 4 , the LUMO level is preferably about 3 to 3.5 eV.

The structure of the device shown may also be reversed so that the cathode rather than the anode forms the bottom electrode of the device.

It is an object of certain embodiments of the present invention to provide an improved method of processing a bottom electrode of a light emitting device to provide good ohmic contact between the improved organic light emitting device and the bottom electrode and the organic semiconductor material disposed thereon.

The active matrix organic light emitting display comprises a matrix of organic light emitting devices forming the pixels of the display. Each organic light emitting device includes an anode, a cathode, and the above-described organic light emitting layer disposed therebetween.

By switching the current flow through them using a memory device, which typically includes a storage capacitor and a transistor, the pixels of the active matrix organic light emitting display can be switched between a light emitting state and a non-light emitting state.

It is an object of certain embodiments of the present invention to provide an improved active matrix organic light emitting display comprising a thin film transistor and an organic light emitting device deposited on a common substrate surface and an improved method of making the same.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a method of fabricating an organic thin film transistor, comprising: depositing a source and a drain electrode; A dopant moiety on the surface of the source and drain electrodes for chemically doping the organic semiconductor material by the acceptance or donation of charges and a separate attachment to the dopant moiety selectively coupled to the source and drain electrodes Forming a thin film self-assembled layer of a material comprising a moiety; And depositing a solution containing a solvent and an organic semiconductor material in a channel region between the source and drain electrodes.

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The use of a separate attachment moiety with the dopant moiety makes it possible to select the dopant moiety so as to achieve a good charge transfer from or to the selected OSC, and it is possible to select the dopant moiety from the channel dielectric (for the bottom-gate device) It is possible to select the attachment moiety so that a good selective attachment to the selected source / drain material is achieved rather than the substrate surface (for the top-gate device) between the drains.

Such an arrangement provides an improvement by the arrangement described in US 2005/133782 wherein the dopant moiety is chosen such that charge transport and attachment to the source / drain electrode is achieved. In particular, the present invention allows for more flexibility to select dopant moieties that are not good for any source / drain electrode materials, or which have no adhesion properties, although these are good dopants. In addition, the present invention provides better flexibility for selectively attaching to source / drain electrodes, but more flexibility for selecting attachment moieties without any dopant properties. For example, the benzonitrile dopants described in US 2005/133782 can be used as p-type dopants for certain OSC materials and can clearly provide some adhesion properties to palladium, but the benzonitrile dopants can be used for other OSC (E.g., they can not be used for n-type doping of n-type OSC materials) and may not provide good selective bonding to other types of source / drain materials. On the other hand, the present invention provides thin self-assembled layers of a material that can be optimized for both charge transport and selective deposition, for both OSC and source / drain materials.

The present invention also makes it possible to determine the source / drain contact using a wide range of materials and to determine the relevant metal tracking that this layer is expected to provide. Materials for their conductivity and processing advantages can be selected without the need for work function of the material to meet specific OSC energy levels. This will make it possible to replace commonly used source / drain electrode materials such as gold (and palladium) with less expensive materials that are easier to pattern.

In addition, it has been found that during operation of the organic thin film transistors, heavy metals such as gold tend to diffuse into the OSC and adversely affect the functional properties of the OSC. The present invention enables selection of source / drain materials that are not affected by these adverse diffusion effects.

Furthermore, it has been found that the use of a separate attachment moiety with a dopant moiety results in a particularly good charge transfer from or to the deposited OSC from the solution state. While not wishing to be bound by theory, it is believed that the attachment moiety results in doping moieties into the solution when the OSC solution is deposited, resulting in better doping during drying of the OSC film.

The attachment moiety may be chemically bonded to the source / drain electrode, for example, by one or more covalent bonds. The attachment moiety may also be chemically bonded to the dopant moiety by one or more covalent bonds, for example. For example, the attachment moiety may include a leaving group such that when the leaving group leaves, the attachment moiety reacts with the source and drain material to form a bond with the material. For example, the attachment moiety may contain at least one of a silyl group, a thiol group, an amine group, and a phosphate group. It will be appreciated that the attachment moieties can be selected by their ability to bond to the surface of the source and drain electrodes and will then depend on the material used for these electrodes. For example, thiols are particularly suitable for bonding to gold and silver, and silanes are suitable for bonding to oxides (for example, SD electrodes made of metal whose surface is oxidized).

Such arrangements can be used to strongly immobilize the dopant moiety to the source / drain electrode, to diffuse from the source / drain during operation, or to remove excess dopant from other areas of the device, such as channel regions, Prevent the moiety from being removed.

The dopant moiety may be an electron acceptor that accepts electrons from the organic semiconductor material, thereby p doping the organic semiconductor material. Preferably, the p dopant easily accepts electrons since the LUMO level is less than -4.3 eV. The organic semiconductor material for use with the p-dopant donates electrons since the HOMO level is equal to or higher than -5.5 eV. Most preferably, for a p-channel device, the LUMO level of the dopant is less than -4.3 eV, and the HOMO level of the organic semiconductor material is equal to or greater than -5.5 eV.

To avoid misunderstandings associated with these negative values, the range "above -5.5 eV or higher" includes -5.4 eV, excluding -5.6 eV, and the range "below -4.3 eV" Including -4.4 eV and excluding -4.2 eV.

It has been found that the combination of a semiconductor organic material having a HOMO level equal to or higher than -5.5 eV and a dopant having a LUMO level of less than -4.3 eV produces a conductive composition in the source and drain contact regions. Although not wishing to be bound by theory, organic semiconductor materials with HOMO levels equal to or higher than -5.5 eV provide good hole transport and incorporation properties, but dopants with a LUMO level of less than -4.3 eV can form free holes in organic semiconductor materials It is assumed that electrons are readily accepted from such organic semiconductor materials.

In the case of a p dopant, the HOMO of the organic semiconductor material is preferably higher (i.e., a lower negative value) than the LUMO of the dopant. This provides better electron transfer from the HOMO of the organic semiconductor material to the LUMO of the dopant. However, if the HOMO of the organic semiconductor material is only slightly lower than the LUMO of the dopant, charge transport is still observed.

The p-type organic semiconductor material preferably has a HOMO in the range of 4.6 to 5.5 eV. This allows the introduction and transport of good holes from the electrodes and through the organic semiconductor material.

The dopant is preferably a charge neutral dopant, and tetracyanoquinodimethane (TCNQ) optionally substituted with an ion species such as a protonic acid doping reagent is most preferable. If a high concentration of acid is provided adjacent to the electrode, the electrode may corrode with the release of the electrode material, causing decomposition of the organic semiconductor material covering the stomach. Moreover, the acid may interact with the organic semiconductor material to cause charge separation that is detrimental to the performance of the device. Therefore, charge neutral dopants such as TCNQ are preferred.

The organic semiconductor material is preferably solution-processed so that it can be deposited by, for example, an ink-jet printing method. Examples of the solution processable materials include polymers, dendrimers, and small molecules.

The optionally substituted TCNQ is preferably a fluorinated derivative such as tetrafluoro-tetracyanoquinodimethane (F4-TCNQ). This derivative has been found to be particularly good for electron acceptance.

The conductivity of the composition is preferably in the range of 10 ^-6 S / cm to 10 ^-2 S / cm near the electrodes. However, the conductivity of the composition can be easily varied by varying the dopant concentration or by using different organic semiconductor materials and / or dopants, depending on the specific conductivity value desired for the particular application.

As an alternative to the aforementioned p-channel devices, the dopant moiety may be an electron donor for donating electrons to the organic semiconductor material, whereby the organic semiconductor material is n-doped.

A spacer group may be provided between the attachment moiety and the dopant moiety. Spacers can be used to better position the dopant moieties within the OSC resulting in better doping. Further, the spacer groups can provide some flexibility in the surface on which the OSC is to be deposited, which can form a better film of the OSC on its surface. The spacer group may be an alkylene chain, for example, a C ₁ -C ₂₀ alkylene chain. The spacers may be of different lengths to form a concentration gradient of the dopant moiety that increases upon approach to the source and drain electrodes.

For bottom-gate devices, the selective bonding of the attachment moieties to the source and drain electrodes is facilitated by utilizing an organic dielectric material to provide a large difference in the chemistry of the dielectric layer and the source and drain electrodes.

Similarly, for top-gate devices, selective bonding of the attachment moieties to the source and drain electrodes is facilitated by using an organic substrate to provide a large difference in the chemical properties of the dielectric layer and the source and drain electrodes do.

In another arrangement, the dielectric layer or the substrate may be treated to enhance selective bonding of the attachment moieties to the source and drain electrodes as opposed to the dielectric layer or the substrate.

In another aspect of the present invention, there is provided an organic thin film transistor fabricated according to the above-described methods. Wherein the organic thin film transistor includes source and drain electrodes and a solution processable organic semiconductor material disposed therebetween in a channel region, wherein the source and drain electrodes are formed on the surface of the organic semiconductor material And a separate attachment moiety that is coupled to the dopant moiety and is selectively coupled to the source and drain electrodes.

According to another aspect of the present invention, there is provided a method of manufacturing a light emitting device,

Depositing a first electrode on the substrate; A dopant moiety for chemically doping the charge transporting organic semiconductor material by receiving or donating charge on the surface of the first electrode and a material comprising the dopant moiety and a separate attachment moiety coupled to the first electrode Forming a thin film self-assembling type layer comprising Depositing a solution comprising a solvent and a charge transporting organic semiconductor material on the thin film self-assembled layer; Depositing an organic light emitting material on the charge transporting organic semiconductor material layer; And depositing a second electrode over the organic light emitting material.

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In accordance with this aspect of the present invention, there is provided a light emitting display having a bottom electrode over which a self-assembled layer of material comprising a dopant moiety and a separate attachment moiety is disposed. A semiconductor material is disposed thereon with a dopant moiety doping the semiconductor material in the bottom electrode adjacent portion for forming a conductive charge injection layer. By attaching the dopant moiety to the electrode, the semiconductor material is more strongly doped adjacent to the electrode, which is advantageous for introducing charge from the anode into the light emitting material disposed thereon. Thus, the present invention provides a substitute for a separately deposited conductive charge transport layer and a semiconductor charge transport layer for use in the prior art.

As described above, the dopant moiety, the attachment moiety and the spacer moiety may be related to the embodiment of the present invention of the organic thin film transistor.

According to another aspect of the present invention, there is provided a light emitting device manufactured according to the above-described method. The organic electroluminescent display according to claim 1, wherein the light emitting display comprises a substrate, a first electrode disposed on the substrate, a second electrode disposed on the first electrode, an organic light emitting material disposed between the first electrode and the second electrode, Wherein the first electrode comprises a dopant moiety for chemically doping a charge transporting organic semiconductor material onto a surface thereof by accepting or donating charge and a dopant moiety for chemically doping the charge transporting organic semiconductor material, And a separate attachment moiety coupled to the first electrode.

In another aspect of the present invention, there is provided an active matrix organic light emitting display comprising a plurality of thin film transistors and a plurality of light emitting devices formed in accordance with another aspect of the present invention. In one particularly preferred embodiment, the bottom electrode of the organic light emitting device and the source / drain electrodes of the organic thin film transistor are doped in a single step process. The doping may be using a common material, or alternatively, co-doping may be used using mixed dopants in a single step.

Hereinafter, the present invention will be described in more detail by way of example only with reference to the accompanying drawings.

Figure 1 shows a known top-gate organic thin film transistor array.

Figure 2 shows a known bottom-gate organic thin film transistor array.

3 shows an organic thin film transistor according to an embodiment of the present invention.

4 illustrates a fabrication step associated with the formation of an organic thin film transistor according to the embodiment mode shown in Fig.

5 shows a schematic diagram of a self-assembly type layer according to an embodiment of the present invention.

Fig. 6 shows a known organic light emitting device arrangement.

7 shows an arrangement of an organic light emitting device according to an embodiment of the present invention.

Fig. 8 shows an organic thin film transistor and an organic light emitting device in a process of forming on a common substrate surface.

9 shows an organic thin film transistor and an organic light emitting device formed on a common substrate surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 3 shows a bottom-gate organic thin film transistor according to an embodiment of the present invention. The structure is similar to the arrangement of the prior art shown in Fig. 2, and for clarity, the same reference numerals are used for the same parts. An important difference of the arrangement shown in FIG. 3 is that the source and drain electrodes 2, 4 accept or charge electrical charges to chemically dope the organic semiconductor material on its surface and a dopant moiety for coupling the dopant moiety to the source and drain A self-assembled thin film layer 14 made of a material containing a separate attachment moiety.

A schematic diagram of the self-assembling mold layer 14 is illustrated in FIG. As a gold or silver source-drain material, a dopant having a thiol-attaching group could be used. A typical dopant molecule is TCNQ or F4TCNQ, which is a lower dopant (electron acceptor) with a lower LUMO and a typical OSC material.

The bottom-gate implementation illustrated in FIG. 3 has been formed using the method shown in FIG. 5 in schematic cross-section.

1. Gate deposition and patterning 12 (e.g., patterning of ITO coated substrates).

2. Dielectric deposition and patterning 10 (e. G., Cross-linking, photopatternable dielectric

sieve).

3. Source-drain material deposition and patterning 2, 4 (e.g., gold, photolithography)

4. Source-drain surface treatment 14 . The surface treatment may be carried out in a self-

Lt; RTI ID = 0.0 > monolayer < / RTI > material or from a dilute solution

By spin coating. Excessive (unattached

The silver material can be removed by cleaning. A hydrophobic organic dielectric material
The dragon allows selectivity, and the attachers < RTI ID = 0.0 >

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Prevents attachment of sieve. When the channel region is doped,

The transistor is in its off-state < RTI ID = 0.0 >
So that current flows from the source to the drain. [Gate bias

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A depletion type thin film transistor for application to turning off the transistor

To produce a stutter, this effect is achieved by controlling the OSC in the channel region

Note that this can be a preferred method for doping.

5. Deposition of the OSC 8 (e.g., inkjet printing of a solution processable polymer

).

6. When the dopant molecules are in contact 16 , the dopant molecules

Interact with the OSC. For LUMO deep receptor dopants,

Electrons are transported from the OSC to the dopant so that the local region of the OSC

It leads to evangelism. This is because the charge at the source and drain contacts

Improves mouth and extraction.

This technique is also applicable to top-gate devices. In this case, the source-drain layer is first deposited and patterned. Subsequently, the surface treatment is applied to the source-drain layer prior to OSC, gate dielectric and gate deposition. Within the source-drain channel region, an attachment moiety for the dopant that is not itself attached to the exposed substrate is selected.

The treatment to prevent adhesion of the dopant can be applied at a specific location. If the selectivity can not be achieved directly, this is the number required to prevent adhesion to the channel region.

If it is necessary to expose the source-drain metal (e.g., for electrical contact to a subsequent conductive layer), the dopant layer may need to be removed (e.g., photoreactive adhesive, direct light patterning, Or the like), or it may require preliminary surface patterning to define where the dopant layer is desired. Alternatively, if the dopant layer is thin and sufficiently conductive, the fund may remain in situ without interfering with conductivity by formation.

The above-described techniques for organic thin film transistors can also be used for organic light emitting devices to improve charge introduction. FIG. 6, which has already been described in the background section, shows the structure of the organic light emitting device according to the prior art device. According to one aspect of the present invention, separate layers of the conductive charge-transporting material 105 and the semiconductor charge transporting material 106 may be formed by depositing a dopant moiety and a separate attachment moiety 0.0 > 150 < / RTI > The dopant moiety dopes the semiconductor material 106 adjacent the bottom electrode 102 to form a conductive charge-entry region having a remaining semiconductor area thereon. By attaching the dopant moiety to the electrode 102 , the semiconductor material is more strongly doped adjacent to the electrode, which is advantageous to introduce charge from the anode into the light emitting material 103 disposed thereon. Moreover, since the dopant moiety is coupled to the bottom electrode 102 , the dopant moiety can not diffuse through the light-emitting device during use, because it is possible to use PEDT-PSS, which is highly acidic, It may be a problem in the prior art when it is used as a conductive hole injection material which is known to have a slight influence.

The degree to which the semiconductor charge transport material is doped can be controlled by using a spacer between the attachment moiety and the dopant moiety. A mixture of dopant molecules having different spacer lengths may be used to provide a controlled concentration gradient of the dopant throughout the semiconductor material. Moreover, the use of separate dopants and attachment moieties allows selection of appropriate attachment moieties for dopants and specific electrode materials that are appropriate for the particular semiconductor material that provides flexibility in device design.

Organic thin film transistors and organic light emitting devices described herein can be used in an active matrix organic light emitting display wherein the organic light emitting devices are sub-active in an active matrix organic light emitting display driven by the organic thin film transistors, And forms a sub-pixel. In one particularly preferred embodiment, the bottom electrode of the organic light emitting device and the source / drain electrodes of the organic thin film transistors are doped in a single step process. The doping may be using a common material or alternatively using simultaneous doping using dopants mixed in a single step. Fig. 8 shows a part of a display during fabrication with an organic thin film transistor and an organic light emitting device formed on a common substrate surface. The structure of FIG. 8A is formed by patterning the ITO-coated substrate, for example, by vapor deposition and patterning of the gate 200 and the anode 202 . The dielectric material 204 is deposited and patterned using, for example, a cross-linkable, photo-patternable dielectric. The source-drain material 206 , 208 is deposited and patterned, for example by depositing a gold layer and patterning using photolithography. Then, a bank material 210 is deposited and patterned to form a bank structure including the organic thin film transistor and the wells 212 and 214 for the organic light emitting device, respectively.

The main steps illustrated in FIGS. 8 (a) through 8 (b) are the source / drain of the organic thin film transistor and the self-alignment of a material comprising a dopant moiety and a separate attachment moiety on the anode of the organic light- Is the deposition step of the build-up layer 216, 218 . As noted above, the attachment moieties are coupled to the dopant moieties and selectively couple to the source / drain and the anodes. In one particularly preferred embodiment, the anode of the organic light emitting device and the source / drain electrodes of the organic thin film transistor are doped in a single step process. This doping can use a common material. Alternatively, simultaneous doping using a mixed dopant may be used, wherein one of the dopants of the mixture selectively couples to the source / drain, and the other dopant of the dopant is selectively coupled to the anode do.

After the doping step, the organic thin film transistor and the remaining layers of the organic light emitting device may be deposited as shown in FIG. An organic semiconductor material 220 is deposited in the channel region between the source and the drain of the organic thin film transistor. A charge transporting organic semiconductor material 222 , a light emitting material 224 , and a cathode 226 are deposited to form an organic light emitting display.

Thus, the techniques described herein can be applied to organic thin film transistors, organic light emitting devices, and active matrix organic light emitting displays. Although the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be apparent to those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims. You will understand that you can do branch transformations.

Claims (31)

Depositing a source and a drain electrode; A dopant moiety on the surface of the source and drain electrodes for chemically doping the organic semiconductor material by the acceptance or donation of charges and a separate attachment to the dopant moiety and selectively coupled to the source and drain electrodes Wherein a spacer group is provided between the attachment moiety and the dopant moiety as a step of forming a thin film self-assembled layer of a material comprising a moiety; And Depositing a solution containing a solvent and an organic semiconductor material in a channel region between the source and drain electrodes Wherein the organic thin film transistor includes a first electrode and a second electrode. The method of claim 1, wherein the thin film self-assembled layer is a self-assembled monolayer. 3. The method of claim 1 or 2, wherein the attachment moieties are chemically bonded to the source and drain electrodes by one or more covalent bonds. 3. The method of claim 1 or 2, wherein the attachment moiety is chemically bonded to the dopant moiety by one or more covalent bonds. 3. The method of claim 1 or 2, wherein the attachment moiety is not a dopant moiety. 3. The method of claim 1 or 2, wherein the attachment moiety comprises at least one of a silyl group, a thiol group, an amine group, and a phosphate group. 3. The method of claim 1 or 2, wherein the organic semiconductor material is solution processable. 3. The method of claim 1 or 2, wherein the doped organic semiconductor material adjacent to the source and drain electrodes has a conductivity in the range of 10 < ^-6 > S / cm to 10 < ^-2 > S / cm. 3. The method of claim 1 or 2, wherein the dopant moiety is a charge neutral dopant. 3. The method of claim 1 or 2, wherein the dopant moiety is an electron acceptor for receiving electrons from the organic semiconductor material, whereby the organic semiconductor is p-doped. 11. The method of claim 10, wherein the dopant has a LUMO level of less than -4.3 eV. 11. The method of claim 10, wherein the organic semiconductor material has a HOMO level equal to or greater than -5.5 eV. 11. The method of claim 10 wherein the HOMO of the organic semiconductor material is higher than the LUMO of the dopant. 11. The method of claim 10, wherein the organic semiconductor material has a HOMO in the range of -4.6 to -5.5 eV. 11. The method of claim 10, wherein the dopant is optionally substituted tetracyanoquinodimethane (TCNQ). 16. The method of claim 15, wherein the optionally substituted TCNQ is a fluorinated derivative thereof. 3. The method of claim 1 or 2, wherein the dopant moiety is an electron donor for donating electrons to the organic semiconductor material, whereby the organic semiconductor is n-doped. 3. A process according to claim 1 or 2, wherein said spacer group comprises an alkylene chain, preferably a C ₁ -C ₂₀ alkylene chain. 3. The method of claim 1 or 2, wherein spacers of different lengths are provided to form an increasing concentration gradient of the dopant moiety upon approaching the source and drain electrodes. The organic thin film transistor of claim 1 or 2, wherein the organic thin film transistor is a bottom-gate device including a gate electrode disposed on a substrate and a dielectric material layer disposed on the gate electrode, Are disposed on the dielectric material. 21. The method of claim 20, wherein the dielectric material comprises an organic dielectric material. 21. The method of claim 20, wherein the dielectric material layer is treated to enhance selective bonding of the attachment moieties to the source and drain electrodes. The organic thin film transistor according to claim 1 or 2, wherein the organic thin film transistor is a top-gate device in which source and drain electrodes are disposed on a substrate, and the organic semiconductor material is disposed on the source and drain electrodes, Region, a dielectric material is disposed over the organic semiconductor material, and a gate electrode is disposed over the dielectric material. 24. The method of claim 23, wherein the substrate comprises an organic dielectric material. 24. The method of claim 23, wherein the substrate is processed to enhance selective bonding of the attachment moieties to the source and drain electrodes. Depositing a first electrode on the substrate; A dopant moiety for chemically doping the charge transporting organic semiconductor material by receiving or donating charge on the surface of the first electrode and a material comprising the dopant moiety and a separate attachment moiety coupled to the first electrode Wherein a spacer group is provided between the attachment moiety and the dopant moiety; Depositing a solution comprising a solvent and a charge transporting organic semiconductor material on the thin film self-assembled layer; Depositing an organic light emitting material on the charge transporting organic semiconductor material layer; And Depositing a second electrode on the organic light emitting material Emitting device. Forming a plurality of thin film transistors conforming to the method of claims 1 or 2 and forming a plurality of light emitting devices following the method of claim 26. A method of manufacturing an active matrix organic light emitting display, 28. The method of claim 27, wherein the source and drain electrodes of the organic thin film transistor and the first electrode of the organic light emitting device are doped with a single deposition step. 29. The method of claim 28, wherein the first electrode of the organic light emitting device and the source and drain electrodes of the organic thin film transistor are doped using a common dopant. 29. The method of claim 28, wherein the first electrode of the organic light emitting device and the source and drain electrodes of the organic thin film transistor are doped using a mixed dopant. delete

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